JPH0614565A - Vibration wave motor control circuit - Google Patents

Abstract

(57) [Abstract] [Purpose] In a lens barrel equipped with a vibration wave motor as a drive source for an autofocus mechanism or a zoom lens mechanism, the user may accidentally hold the zoom ring or focus ring by hand. When trying to start the motor, the rotor may be in a fixed state, which may make it impossible to start the motor. In such a case, in the conventional control circuit, the frequency of the drive signal given to the stator when the motor is started is sequentially changed from the high frequency to the low frequency, and when the rotor still does not start, the motor of the control circuit is changed. The startup operation was completed. The present invention provides a control circuit that eliminates the drawbacks of conventional activation control methods. According to the control circuit of the present invention, the frequency of the drive signal applied to the stator when the motor is started is sequentially changed, and the phase of the drive signal is also controlled.
Therefore, a larger torque than before can be applied to the rotor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention generates a progressive vibration wave on the surface of a vibrating body by applying a frequency voltage to an electro-mechanical energy conversion element such as an electrostrictive element or a piezoelectric element, and moves by the vibration wave. The present invention relates to a control circuit for a vibration wave motor that drives a body.

[0002]

2. Description of the Related Art There is known a method of changing the frequency of the frequency voltage when adjusting the speed of a motor of this type.

When the motor is set to a desired speed by the method, a frequency corresponding to the desired speed may be selected and applied to the electro-mechanical energy conversion element. The rotation will start.
Further, since the correspondence relationship between the speed and the frequency is influenced by the environmental conditions such as temperature, there is a disadvantage that the speed varies depending on the environmental conditions.

Therefore, in order to rotate the motor smoothly and to drive the motor at a stable speed even with a slight change in environmental conditions, the drive frequency is gradually decreased from a high frequency when the motor is started, After confirming the start of, compare the actual rotation speed with the desired rotation speed,
If the actual rotation speed is faster than the desired rotation speed, the frequency is shifted to the high frequency direction, and if the actual rotation speed is slower than the desired rotation speed, the frequency is shifted to the low frequency direction to obtain the desired The frequency may be controlled so as to obtain the speed of.

At this time, the high frequency at the time of starting is set to a frequency at which the motor actually starts rotating, and if the frequency is gradually decreased from this set frequency, the motor is driven smoothly to a desired speed in a short time. Although you can
The characteristics of the above motors are not constant and are affected by environmental changes such as temperature.If the frequency at the start of starting is fixed, it will not be possible to cope with changes in temperature, etc. There is a possibility of starting a proper rotation and, in the worst case, not starting.

As a method for solving the above problem, for example, Japanese Patent Laid-Open No. Sho. That is, this is a method of storing the movement start frequency at the time of the previous activation and scanning from the stored frequency to a low frequency when moving next time. This starting method is based on the fact that it has been started in the past, remembers its starting frequency, and refers to the method of frequency scanning at the next starting. Further, when the vibration wave motor is installed in the zoom lens barrel for a single-lens reflex camera as a drive source for autofocus and autozoom, the zoom lens is not used while the lens barrel is in use. Although it may hit the end or the focus ring or the like may be stopped by hand, in such a case, the operation of the drive circuit is ended in the unstartable state by the conventional starting method. In such a case, the information on the starting frequency is not useful, so when starting the next time after the unstartable state, the frequency scan is started from the highest frequency in the settable range.

Starting the motor due to the zoom lens hitting the wide end or the tele end or the focus lens being stopped by hand despite scanning from the high frequency to the low frequency by the above method If it is not possible, in order to solve the problem of the conventional start-up method that the operation of the drive circuit is terminated in the unstartable state as it is, the start-up is performed again from the highest frequency in the settable range to the low frequency. A method has been proposed and this method has already been put to practical use.

After the motor can be started, it is necessary to perform control to bring the rotation speed of the motor close to a desired rotation speed. As a method therefor, speed control and phase control are well known.

In the speed control, the rotation speed of the motor is detected at a certain cycle, the obtained rotation speed is compared with the desired rotation speed, and if the actual rotation speed is faster than the desired rotation speed, the frequency is determined. The value is increased, and the frequency is decreased by a predetermined value when the actual rotation speed is slower than the desired rotation speed. By changing the cycle for detecting the rotation speed of the motor, control can be speeded up or slowed down according to the response speed of the motor. Regarding the width of increasing and decreasing the frequency, there are a uniform method and a method of changing the width according to the ratio of the actual rotation speed to the desired rotation speed.

The phase control detects the phase difference between the frequency voltage applied to the electrostrictive element group disposed on the stator of the vibration wave motor and the frequency voltage obtained from the sensor electrostrictive element, and detects the phase difference obtained. It is a method of controlling the frequency based on information.
As a characteristic of the vibration wave motor, when the frequency is gradually decreased from the higher frequency, and the motor starts rotating and the speed is gradually increased, the phase gradually approaches the resonance state. And
When the phases are in resonance, the rotation speed of the motor reaches near the maximum speed. When the frequency is further reduced from the resonance state, the rotation speed rapidly decreases and the phase also deviates from the resonance state. Therefore, in order to prevent the phase from proceeding from the resonance state to the direction of lower frequency, when the phase is being detected and approaching the resonance state, it is necessary to perform control to return the frequency to the higher side.

By the way, the relationship between the rotation frequency and the phase of the vibration wave motor and the frequency is almost as shown in FIG. F
_btr is a frequency at which the motor starts to rotate, and the rotation speed is increased by gradually decreasing from the frequency. The phase is a function that approaches the resonance state almost simply with respect to the frequency until the maximum speed is reached after the motor is started. In the phase control, for example, an actual phase signal is detected, compared with θ ₁ in FIG. 9, and when the phase exceeds θ ₁ , the frequency is returned to a higher side. When the frequency is scanned from F _max to start the motor, the phase is unstable as shown in FIG. 9 until the movement start frequency F _btr is reached, and the phase returns to the resonance direction, a phenomenon called phase return. Occurs. Therefore, if the above-mentioned control to return the frequency to the higher side when the phase exceeds θ ₁ is performed before the motor starts rotating,
There is an inconvenience that normal acceleration cannot be performed due to the phase shift. Therefore, normally, the phase control is not performed until the motor is started. In addition, the phase is unstable even when the zoom lens hits the wide end or the tele end during use of the lens barrel or the movable part of the focus lens is stopped by hand.

Generally, the vibration wave motor is controlled by combining the speed control and the phase control described above. In the speed control, the rotation speed of the motor is stably rotated at a high speed and smoothly stopped, and the phase control is performed. Has the implication of avoiding a sudden stop of the motor. A method is often used in which the frequency is reduced at a constant cycle when the motor is started, phase control and speed control are performed after the motor is started, and only speed control is performed when the motor is stopped.

[0013]

However, in the above-mentioned conventional example, in the case where the movable portion of the focus lens is a lens outside, the starting torque is small due to the performance of the motor itself, and Due to causes such as when the starting torque becomes smaller due to
If the moving part of the focus lens is stopped by hand when starting the motor, and the motor cannot be started at all due to the small starting torque of the motor, the operation of the drive circuit is terminated there. Either it will end up or the operation of the drive circuit will end after rescanning, so it will stop immediately after doing the circuit operation for trying to start the motor for a very short time . Therefore, the user cannot even recognize that the drive circuit is trying to start the motor, and no matter how many times the drive circuit tries to start the motor, the user such as the camera does not try to release the moving part of the focus lens, Therefore, there is a problem that an accurate autofocus operation cannot be performed.

[0014]

According to the present invention, the movable part of the focus lens is stopped by hand even though the frequency scan is gradually performed from the high frequency to the low frequency. If it cannot be started, the frequency scan is performed again from the highest frequency in the settable range, and the phase control during normal operation is also performed this time for a predetermined time, so that the frequency does not fall below the resonance frequency. Therefore, even if the motor cannot be started, the frequency is controlled without immediately ending the operation of the drive circuit.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a first embodiment of the present invention, in which a vibration wave motor and a control circuit for controlling the vibration wave motor are built in a lens barrel.

In the figure, 1 is a microcomputer. 2 is D / A
In the converter, the digital output signal (D /
Aout) has the function of converting into an output voltage. A voltage controlled oscillator (VCO) 3 outputs a frequency voltage according to the output voltage of the D / A converter 2. 4 is a frequency divider / phase shifter,
The frequency voltage of the VCO 3 is divided and a rectangular wave with a π / 2 phase difference is output. Power amplifiers 5 and 6 amplify the frequency voltage of the frequency divider / phase shifter 4 to a voltage and a current value capable of driving the vibration wave motor 9. 7 and 8 are matching coils, 9 is a vibration wave motor, 9a is a rotor, and 9b is a stator. Reference numeral 10 denotes a pulse plate, which has a plurality of slits opened in the radial direction as shown in the figure, is coaxial with the shaft of the vibration wave motor 9 together with the gear 11, and rotates together with the rotor 9a of the vibration wave motor 9. Reference numeral 12 denotes a gear, which is fitted to the outer peripheral gear portion of the lens barrel 13. 14 is a lens. An interrupter 15 detects the rotation of the pulse plate 10. 16 is an interrupter 15
The signal detection circuit of (1) amplifies the minute signal of the interrupter 15 and converts it into a digital signal. 17 is up / dow
The n counter counts pulse signals generated by the rotation of the pulse plate 10. 18 is a memory for lens data,
It stores the open F value, the focal length, and the speed table for driving the focus lens, which are unique to the lens. 1
Reference numerals 9 and 20 are phase comparators, and by comparing with a reference voltage generated by the voltage dividing resistors 21 and 22, A phase and S
Shape the phase waveform so that it can be input to the microcomputer.

Next, each terminal of the microcomputer 1 will be described.

DIR1 is an output terminal for instructing the counting direction of the up / down counter 17, and for convenience of explanation, "H" is up and "L" is down. PULSE
IN is an input terminal for the count value of the up / down counter 17. MON is a direct monitor input terminal for the output of the detection circuit 16. RESET is a reset output terminal of the up / down counter 17 and is reset by "H". CN
T EN / | DIS is an output terminal for the count enable / disable instruction of the up / down counter 17, which is enabled by "H" and disabled by "L". D / Aout is an output terminal to the D / A converter 2. The DIR 2 gives the frequency divider / phase shifter 4 an instruction to change the phase difference between the frequency voltages A and B applied to the vibration wave motor 9 to 90 ° and 270 ° in order to switch the rotation direction of the vibration wave motor 9. Output terminal. USM EN / ￣ DIS is a terminal for turning on / off the output of the frequency divider / phase shifter 4, and is “H” for O.
N, "L" turns off. AIN and SIN are input terminals of waveforms obtained by shaping the A-phase and S-phase waveforms by the comparators 19 and 20, respectively. ADDRESS is an output terminal for designating an address of the lens data memory 18, and designates which data is input. DATA
IN is an input terminal for the data stored in the address on the lens data memory 18, which is designated by being output to the ADDRESS terminal.

Next, the vibration wave motor 9 will be described with reference to FIG.

FIG. 2 is an explanatory view showing the arrangement of electrostrictive elements arranged on the back surface of the stator 9b. A ₁ and B _{1 in} FIG. 2 are the first and second electrostrictive element groups arranged on the stator 9b in the illustrated phase and polarization relationship, respectively. Further, S ₁ is an electrostrictive element for a sensor arranged at a position shifted in phase by 45 ° from the first electrostrictive element group B ₁ . Each of these electrostrictive elements may be individually attached to the vibrating body, or may be integrally formed by polarization treatment. Returning to FIG. 1, A, B and S are respectively the first and second
Drive electrodes and sensor electrodes for the electrostrictive element group and the sensor electrostrictive element S ₁ are shown. A frequency voltage is applied to the electrode A via the amplifier 5 and a frequency voltage is applied to the electrode B via the amplifier 6. By applying the voltage, a progressive vibration wave is formed on the back surface of the stator 9b. Further, when the vibration wave is formed on the vibrating body, the sensor electrostrictive element S outputs (frequency voltage) according to the state of the vibration wave.
Is output, and this is detected by the sensor electrode S ₁ .
In the resonance state, the vibration wave motor has a characteristic that the phase relationship between the drive voltage to the A electrode and the output voltage from the sensor electrode has a specific relationship, and a frequency signal is applied to the electrode A. First electrostrictive element group A ₁ and sensor electrostrictive element S
In the case of the present embodiment, a resonance state is shown when the phase of the signal waveforms of the electrodes A and S deviates by 135 °, and a phase difference of 45 ° occurs when reversing. It is assumed that a resonance state is sometimes shown, and the phase relationship shifts as it deviates from resonance.

3, FIG. 4, FIG. 5, FIG. 6, and FIG. 7 are program diagrams showing a program flow programmed in the ROM incorporated in the microcomputer 1 of FIG. The control operation is executed according to

Next, the operation of the embodiment shown in FIG. 1 will be described. When entering the vibration wave motor drive control routine, step 1 is first executed. The operation of each step will be described below.

[Step 1] The flag SSFLAG indicating that rescanning is being performed is reset.

[Step 2] The initial value of the up / down counter 17 is input from the PULSE IN terminal and stored in the variable FPC _OLD .

[Step 3] The value of the variable FMAX is transferred to the variable FREQ. Note that FMAX is an initial frequency determined based on the driving frequency when driven last time, and is the frequency when it is confirmed that movement has started when stopped normally last time (O when stopped in a drive impossible state). Is stored. Further, the values actually output to the D / A _out terminal are directly stored in these variables FMAX and FREQ, and the smaller the value, the higher the driving frequency.

[Step 4] The FREQ value set in step 3 is output to the D / A _out terminal. As a result, the D / A converter 2 converts the digital voltage value output from the D / A _out terminal into an analog voltage and outputs it to the VCO 3. The VCO 3 converts the voltage output from the D / A converter 2 into a frequency and outputs the frequency to the frequency divider / phase shifter 4.

[Step 5] The drive rotation direction is determined,
In the case of forward rotation, the process proceeds to step 6, and in the case of reverse rotation, the process proceeds to step 7.

[Step 6] Since the drive rotation direction is forward rotation, "H" is output to the DIR1 terminal to up / down.
The count direction of the n counter 17 is set to the up direction. In addition, "H" is output to the DIR2 terminal to set the phase difference between the signals A and B output from the frequency divider / phase shifter 4 to 90 °,
Go to step 8.

[Step 7] Since the driving rotation direction is reverse rotation, "L" is output to the DIR1 terminal to up / down.
The count direction of the n counter 17 is set to the down direction. Further, "L" is output to the DIR2 terminal to set the phase difference between the signals A and B output from the frequency divider / phase shifter 4 to 270 °, and the process proceeds to step 8.

[Step 8] CNT EN / ￣DIS
"H" is output to the terminal and the up / down counter 17 is set to the count enable state.

[Step 9] USM EN / ￣DIS
"H" is output to the terminal and the outputs A and B of the frequency divider / phase shifter 4 are enabled. As a result, the frequency divider / phase shifter 4 becomes V
A signal is output from A and B according to the frequency according to the voltage output from CO3 and the phase difference according to the level output from the DIR2 terminal. The output signals A and B are amplified by the power amplifiers 5 and 6 and applied to the vibration wave motor 9 via the matching coils 7 and 8. This causes the vibration wave motor 9 to start rotating.

[Step 10] 0 in the variable TIMER2
To store. The TIMER 2 is a counter for measuring the time for performing the phase control during the rescan.

[Step 11] 0 in the variable TIMER1
To store. Note that TIMER1 is a counter for measuring a fixed time when the frequency is lowered each time a fixed time elapses when the rotational movement of the motor is not detected.

[Step 12] A constant ACC is added to FREQ.
Add EL1 and store in FREQ.

[Step 13] If FREQ is greater than the lowest frequency MINFREQ within the settable range, proceed to step 14, otherwise step 20.
Go to.

[Step 14] Since pulse input is not recognized even when the frequency is scanned up to MINFREQ in step 13, it is determined that the driving is impossible, and 0 is stored in the next scan start frequency FMAX.

[Step 15] If the rescan is being performed, the process proceeds to step 19, and if not, the process proceeds to step 16.

[Step 16] The value of the variable FMAX is transferred to the variable FREQ.

[Step 17] The FREQ value set in step 16 is output to the D / A _out terminal.

[Step 18] A flag SSFLAG indicating that rescanning is being performed is set, and the process proceeds to step 8.

[Step 19] Since the motor could not be started despite rescanning, drive end processing is performed.

[Step 20] FR the D / A _out terminal
The value of EQ is output.

[Step 21] The counter value is input from the up / down counter 17 and stored in the variable FPC.

[Step 22] Variable FPC and FPC
_OLD is compared, and if they are equal, the process proceeds to step 23, and if they are not equal, the process proceeds to step 26. That is, the detection circuit 16 detects the rotation operation of the pulse plate 10 to detect up / down.
When the n counter 17 performs counting operation, FPC
Since ≠ FPC _OLD , the process proceeds to step 26. Also,
FPC = when rotation of the pulse plate 10 is not detected
It will be FPC _OLD , so proceed to step 23.

[Step 23] Since the rotation operation of the pulse plate 10 is not detected, the phase control is performed.

[Step 24] The variable TIMER1 is incremented.

[Step 25] It is determined whether or not TIMER1 is equal to the predetermined time TIME_LMT1, and if equal, the process proceeds to step 11. If they are not equal, the process proceeds to step 20.

[Step 26] Since the rotational movement of the pulse plate 10 is detected in step 22, the frequency FREQ at that time is stored in FMAX.

[Step 27] The direction of rotation of the motor is discriminated. If it is normal rotation, the routine proceeds to step 28, and if it is reverse rotation, the routine proceeds to step 29.

[Step 28] It is determined whether or not the phase difference between the A phase and the S phase input from the AIN terminal and the SIN terminal is smaller than 135 ° + phase margin value ROOM22. If smaller, the process proceeds to step 30. Otherwise, go to step 31.

[Step 29] It is determined whether or not the phase difference between the A phase and the S phase input from the AIN terminal and the SIN terminal is smaller than 45 ° + phase margin value ROOM12. If smaller, the process proceeds to step 30. Otherwise step 3
Go to 1.

[Step 30] Since the phase is proceeding further from the resonance state, the frequency is returned to the higher side by the predetermined value ACCEL5.

[Step 31] Since the phase signal has a margin, speed control is performed.

[Step 32] It is checked whether or not the variable FRPC is larger than 0. That is, it is judged whether the remaining drive amount is still present, the target drive amount has already been driven, or whether the vehicle has overrun. If the remaining drive amount is still present, the process proceeds to step 27, and if not, the step 33. Go to.

[Step 33] FRPC ≦ 0, that is, since the target drive amount has already been driven or overrun has occurred, the drive processing is ended.

Steps 34 and 35 are a driving end subroutine.

[Step 34] USM EN / ￣DI
Output "L" to S terminal and output A, B of frequency divider / phase shifter 4
To disable. As a result, the motor stops driving.

[Step 35] USM EN / ￣DI
Outputs "L" to the S terminal, and up / down counter 17
To disable the count.

Steps 36 to 39 are speed control subroutines.

[Step 36] The actual speed of the motor is compared with the target speed previously stored in the ROM on the basis of the information such as the remaining drive amount. If the actual speed is faster than the target speed, the step is performed. Proceed to 37, and if late, proceed to step 38.

[Step 37] Since the speed is fast,
The value obtained by subtracting the constant ACCEL3 from FREQ is stored in FREQ, the frequency is scanned to the higher side, and then the process proceeds to step 39.

[Step 38] Since the speed is slow,
The value obtained by adding the constant ACCEL2 to FREQ is stored in FREQ, the frequency is scanned to the lower side, and then the process proceeds to step 39.

[Step 39] Set the value of FREQ to D / A
Output to the _out terminal.

Steps 40 to 46 are a phase control subroutine that is executed until the motor is started.

[Step 40] It is determined whether or not the rescan is being performed. If the rescan is being performed, the process proceeds to step 41. If not, the process returns.

[Step 41] The variable TIMER2 is incremented.

[Step 42] It is determined whether or not TIMER2 is equal to the predetermined time TIME_LMT2, and if they are equal, the process returns. If they are not equal, the process proceeds to step 43.

[Step 43] The rotation direction of the motor is discriminated, and if it is normal rotation, the routine proceeds to step 44, and if it is reverse rotation, the routine proceeds to step 45.

[Step 44] It is determined whether or not the phase difference between the A phase and the S phase input from the AIN terminal and the SIN terminal is smaller than 135 ° + phase margin value ROOM11. If smaller, the process proceeds to step 46, If not, return.

[Step 45] It is determined whether or not the phase difference between the A phase and the S phase input from the AIN terminal and the SIN terminal is smaller than 45 ° + phase margin value ROOM21. If smaller, the process proceeds to step 46, If not, return.

[Step 46] Since the phase is proceeding further from the resonance state, the frequency is returned to the higher side by the predetermined value ACCEL4.

In the above operation, steps 1 to 10 are initializing at the time of startup, and up / down
The start of the motor is started by confirming the initial state of the counter 17, outputting the scan start frequency, discriminating and setting the rotating direction, initializing variables, and the like.

At steps 11 to 26, confirmation of whether the program has started up and frequency scanning are performed. In the frequency scan, the frequency is lowered every time TIME_LMT1 passes for a certain period of time. Until the activation is confirmed, steps 11 → 12 → 13 → 2 until a certain time has elapsed.
0 → 21 → 22 → 23 → 24 → 25 → 20 → ... is repeated, and when a certain time has elapsed, the process returns from step 25 to step 11 and the frequency is set to the predetermined value ACC in step 12.
Lower EL1 only.

If the start of the motor is confirmed in step 22, the frequency at that time is stored in step 26. However, if the frequency exceeds the predetermined value MINFREQ in step 13 without confirming the start of the motor, the focus is determined. It is determined that the movable portion of the lens is in an inoperable state, such as being pressed by hand, and the process proceeds to a routine for preparing for frequency rescan in steps 14 to 19.

In steps 14 to 19, the processing is shifted to scanning.

In steps 14 to 19, the scan start frequency is set to the highest frequency in the settable range. When this routine is first visited after the start of drive processing, SSFLA
Since G is reset, rescanning is performed from the highest frequency. When this routine is once visited in the past, SSFLAG is set, so that the driving process is ended, and the scanning is not repeated three times or more in one driving process.

In steps 27 to 32, motor phase control and speed control are performed. First, the phase signal is checked, and when the phase is further progressing from the resonance state, the frequency is increased by the predetermined value ACCEL5 to avoid only the situation where the motor suddenly stops. If phase control is not applied, speed control is performed. That is, when the speed is higher than the target speed, the frequency is increased by the predetermined value ACCEL3, and when it is slow, the frequency is decreased by the predetermined value ACCEL2. Due to the characteristics of the vibration wave motor, if the frequency is lowered further than near the maximum speed, the speed will drop sharply. Therefore, it is better not to change the frequency very much near the maximum speed. Therefore, small values are set for the predetermined values ACCEL2 and ACCEL3.

Steps 40 to 46 are the phase control subroutine before the motor is started, but the phase control is not performed during the first scan immediately after the start of the drive processing. During the rescan, the variable TIMER2 is set to the predetermined time TIME_LMT.
Phase control is performed until the value reaches 2, and no phase control is performed thereafter. That is, the time for performing the phase control during the rescan is limited.

[Other Embodiments] FIG. 8 shows a second embodiment of the present invention, in which a camera body is provided with a vibration wave motor and a control circuit for controlling the same. .

In the figure, 23 is a slip mechanism and 24 is a slip mechanism.
Is a camera side transmission mechanism, 25 is a camera side coupling member, 26 is a lens side coupling member, and 27 is a lens side transmission mechanism. t
₁ ~t ₄ is a terminal for the camera and lens communicate, t ₁ is the address output terminals, t ₂ is the address input terminals, t ₃ is the lens data input terminal, t ₄ is the lens data output terminal.

The driving force of the vibration wave motor 9 is the gear 11, the slip mechanism 23, the camera side transmission mechanism 24, the camera side coupling member 25, the lens side coupling member 26, and the lens side transmission mechanism 2.
7 is transmitted to the focusing optical system via the gear 12. The slip mechanism 23 is, for example, when the focusing optical system is stopped at the infinity focusing position or the near focusing position,
This is to prevent the load from reaching the vibration wave motor 9 when a large load is applied to the transmission mechanism, and slips when a load higher than a certain level is applied to the output side.

Data exchange between the camera and the lens is performed using the communication terminals t _{1 to} t ₄ . When the camera outputs the address of the lens data memory 18 storing the lens data to be input to the ADDRESS terminal,
The address information is transmitted to the lens data memory 18 via the address output terminal t ₁ and the address input terminal t ₂ . In response to this, the lens data memory 18 outputs the lens data stored at the designated address, is transmitted via the lens data output terminal t ₄ and the lens data input terminal t _3, and is output from the DATA IN terminal. input.

Regarding the control method for starting the vibration wave motor,
It is similar to the first embodiment.

As described above, when the scan is performed from the high frequency to the low frequency and the value of the low frequency which is not confirmed to be activated exceeds the value of the low frequency, the starting torque of the motor is small and the focus lens is movable. In order to make the user recognize that it is impossible to start normally because the user holds down the part by hand,
Frequency rescan is being performed. At that time, the phase control is performed. When the movable part of the focus lens is held down by hand, the phase signal is in an unstable state, and the phase is controlled to increase the frequency. On the other hand, since the acceleration is performed until the start of the motor is confirmed, the frequency is controlled to be lowered. In this way, since the component for increasing the frequency and the component for decreasing the frequency coexist, the frequency becomes stable in a certain fixed range. Therefore, a certain frequency is continuously applied to the motor, so that the motor tries to continue operating for a while. As a result, the starting torque of the focus lens becomes tenacious, the momentum is transmitted to the lens barrel, and shock is applied to the user's hand,
The user can release the lens barrel of the lens and perform normal lens driving and autofocus operation thereafter.

Even when the focus lens hits the closest end or the infinite end, the motor tries to continue operating for a long time, but since the time for performing the phase control during the rescan is limited, the motor does not move until it hits the end. The driving process is ended after a predetermined time has elapsed. This prevents the power consumption from increasing and the lens or the like from falling into the hang-up state while hitting the fixed end.

[0086]

As described above, when the motor is started, the frequency is scanned from the high frequency to the low frequency, and when the start is confirmed, the phase control and the speed servo control are performed to start the motor. If not confirmed, frequency rescan is performed and phase control is performed, so in a lens that has a structure in which the movable part of the focus lens is exposed to the outside, the starting torque is small due to the performance of the motor itself. In some cases, such as when the starting torque becomes small due to a drop in the power supply voltage, the user unintentionally presses the moving part of the focus lens with his or her hand and cannot start the motor. Scans again from the highest frequency and tries to start the motor. Moreover, the phase signal is also checked during the rescan. When the movable part of the focus lens is pressed down by hand, the phase signal is in an unstable state. When checking the phase signal in this state, it is detected that the phase is proceeding further from the resonance state, so phase control is applied,
Try to raise the frequency. On the other hand, since it is accelerating to try to start the motor, it tries to lower the frequency. Thus, until the motor starts during frequency rescan, it tries to increase the frequency on the one hand and lowers the frequency on the other hand, so the frequency will settle within a certain range and the motor will start. Until it keeps giving a constant frequency. Therefore, in the conventional method, the phase control is not performed even if the frequency is rescanned.Therefore, the vibration wave motor scans in a very short time to the outside of the frequency range where it can move, and acts to start the motor. Although it ended in a moment, since the present invention tries to control the motor at a predetermined frequency until it can be started, the act of starting the motor is continued for a long time. Become. As a result, the driving force of the motor is continuously output, and the user's hand touching the lens barrel feels that he / she is trying to drive the lens. When the user notices that he / she is touching and tries to release his / her hand, it becomes possible to let the user recognize that normal lens drive cannot be performed when the lens barrel is touched. Also, if a lens hits the fixed end,
When the user intentionally grabs the lens barrel,
The control circuit tries to keep the motor running forever, but it limits the time to perform the phase control, thus preventing the increase in power consumption and the risk of falling into a hangup state without starting. . In this way, the user can feel the torque even when the starting torque of the motor is small, so that the lens can be driven and the autofocus operation can be performed normally.

[Brief description of drawings]

FIG. 1 is a block diagram showing a first embodiment of the present invention.

FIG. 2 is an explanatory diagram illustrating a disposition state of electrostrictive elements disposed on a back surface of a stator 9b in FIG.

FIG. 3 is a flowchart showing an embodiment of the present invention.

FIG. 4 is a flowchart showing an embodiment of the present invention.

FIG. 5 is a flowchart showing an embodiment of the present invention.

FIG. 6 is a flowchart showing an embodiment of the present invention.

FIG. 7 is a flowchart showing an embodiment of the present invention.

FIG. 8 is a block diagram showing a second embodiment of the present invention.

FIG. 9 is a diagram showing frequency characteristics of a phase and a rotation speed of a vibration wave motor.

[Explanation of symbols]

1 ... Microcomputer 2 ... D / A converter 3 ... VCO 4 ... Frequency divider / phase shifter 5, 6 ... Power amplifier 7, 8 ... Coil 9 ... Vibration wave motor 9a ... Rotor 9b ... Stator 10 ... Pulse plate 11, 12 ... Gear 13 ... Lens barrel 14 ... Lens 15 ... Interrupter 16 ... Detection circuit 17 ... Up / dow
n counter 18 ... Lens data memory 19, 20 ... Comparator 21, 22 ... Voltage dividing resistor 23 ... Slip mechanism 24 ... Camera-side transmission mechanism 25 ... Camera-side coupling member 26 ... Lens-side coupling member 27 ... Lens-side transmission mechanism t ₁ … Address output terminal t ₂ … Address input terminal t ₃ … Lens data input terminal t ₄ … Lens data output terminal A ₁ , B ₁ , S ₁ … Electrostrictive element group

Claims (1)

[Claims] 1. A control of a vibration wave motor for applying a frequency signal to an electro-mechanical energy conversion element arranged in a vibrating body to form a progressive vibration wave in the vibrating body and driving a moving body by the vibrating wave. In the circuit, rotation detection means for detecting rotation of the motor, speed detection means for detecting rotation speed of the motor, speed setting means for setting an optimum speed according to characteristics of the motor, and at the time of starting the motor. The frequency signal is changed from a predetermined frequency to a low frequency direction, and after the rotation detecting means detects that the motor is rotating, the speed set by the speed setting means and the speed detecting means detect the speed. A frequency adjusting means for comparing the actual speed that has been set, and changing the frequency based on the comparison result;
A specific phase difference that detects a phase difference between a frequency signal generated in a vibration-detecting mechanical-electrical energy conversion element fixed to the vibrating body and the drive frequency signal, and the phase difference approximately represents the resonance state of the motor. A detection circuit that generates an output when the output signal becomes, and a prohibition unit that prohibits the frequency adjustment unit from changing the frequency in the decreasing direction in response to the output of the detection circuit,
And a clocking means for keeping the prohibiting means in an operation permitting state for an arbitrary time, and the motor is rotating by the rotation detecting means in spite of trying to start the motor by the frequency adjusting means. If it cannot be detected, the frequency signal is changed from the predetermined frequency to the low frequency direction again, and the predetermined time is measured by the time measuring means, and the shift of the frequency of the drive frequency signal from the resonance frequency to the low frequency is prohibited for the predetermined time. A control circuit for a vibration wave motor characterized by the above.